The present invention relates to a cutting tool insert comprising of a body of a hard alloy of cemented carbide, cermet, ceramics and cubic boron nitride based materials and a coating designed to be used in metal cutting applications generating high tool temperatures. Said coating comprises at least one thermally stable, textured (Ti,Al,Cr,Me) based nitride, carbonitride, oxynitride and/or oxycarbonitride layer, where Me is one or more of the elements: Zr, Hf, V, Nb, Ta, Mo, W or Si. The coating is grown by physical vapour deposition (PVD) and preferably by cathodic arc evaporation.
Since the mid 1980's, efforts have been made to improve the properties, e.g., wear resistance and hence the performance of tool coatings. At that time, the common practice was to coat cutting tools with TiN. However, TiN suffers from poor oxidation resistance. Improved heat resistance have been achieved by alloying Al in (Ti,Al)N. To further enhance the performance of tool coatings, a wide range of ternary and quaternary systems have been investigated, some with good and some with poor results. One of the most crucial parameter in this research is to achieve a good control of the solubility behavior of the alloying elements and in turn how this would yield an optimized coating performance. Recently, it has been shown that alloying Cr in (Ti,Al,Cr)N improves the coating behavior metal cutting applications.
JP 7237010 discloses a coated cutting tool at least one layer selected from (Ti,Al,Cr)C, (Ti,Al,Cr)N or (Ti,Al,Cr)(C,N) and at least one layer of Ti, TiC, TiN or TiCN.
JP 4128363 discloses a (Ti1-x-yAlxCry)N layer where x<0.8 and 0.2<y<0.7.
JP 2000038653 discloses a (Ti1-x-yCrxAly)N layer where 0.02≦x<1.0 and 0.02≦y≦0.7.
EP 1219723 discloses a hard coating for cutting tools composed of (Ti1-a-b-c-dAlaCrbSicBd)(C1-eNe) where 0.5≦a≦0.8, 0.06≦b, 0≦c≦0.1, 0≦d≦0.1, 0≦c+d≦0.1, a+b+c+d<1 and 0.5≦e≦1.
EP 1132498 discloses a hard wear resistance coating comprising one or two layers of (AlaTibCrc) (NwO1-w) where 30≦a≦70, 30≦b≦70, 0.5≦c≦20, a+b+c=1 0 0 and 0.7≦w≦0.9.
EP 1947209 discloses a first layer of (Cr1-xMx)(BaCbN1-a-b) where 0≦x≦0.7, 0≦a≦0.2 and 0≦b≦0.5 and M is at least one of the elements W, V, Mo, Nb, Ti and Al and a second layer of (Ti1-X-YCrXAlYLZ)(BBCAN1-A-B) where 0≦1-X-Y≦0.5, 0<X≦0.5, 0.4≦Y≦0.7, 0≦Z≦0.15, 0≦A≦0.5, and 0≦B≦0.2 and L is at least either of Si and Y.
As mentioned, the metal cutting industry is continuously looking for new hard coatings with improved high temperature wear resistance and is partly biased by the ongoing development of advanced work material as well as the need for an increased productivity. In turn, these aspects typically results in an increase of the tool temperature during a cutting operation. Hence, the problem to be solved by the present invention focuses on how to provide an alternative method for making a coated cutting tool insert, drill or endmill.
It is an object of the present invention to provide a coated cutting tool insert yielding improved performance in metal cutting applications at high tool temperatures.
Surprisingly, it has been found that by alloying Cr in (Ti,Al)N and adding small amounts of the metal elements Me: Zr, Hf, V, Nb, Ta, Mo, W and/or Si in a textured (Ti,Al,Cr,Me)(C,O,N) layer structure onto a cutting tool insert improves the tool life at machining operations generating high tool temperatures.